This invention relates generally to a flexible tube used for a vacuum system, in which vacuum equipment is connected via such a vacuum tube.
A flexible tube has been used for piping between two or more vacuum devices or equipment. A conventional flexible tube is made of thin sheet metal and is shaped to have an uneven surface with projected parts and depressed or concave parts. If a machine tool or some other hard parts hits the projected parts of a flexible tube, the projected parts of the tube would be deformed and/or broken; and as a result, a vacuum leak might occur. A flexible tube for a vacuum system is usually subjected to a large pressure difference between atmospheric pressure and vacuum pressure. Therefore, such a flexible tube may be deformed or broken due to the pressure difference between the interior and exterior. If a flexible tube is accidentally in contact with an electric wiring, a short circuit might occur and small holes would be formed in the flexible tube.
Accordingly, an object of the present invention is to provide a flexible tube, which is well protected from pressure difference and mechanical shock. Additional objects, advantages and novel features of the present invention will be set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentality and combinations particularly pointed out in the appended claims.
According to the present invention, a flexible tube for a vacuum system includes a tube body and a cover. The tube body is made of hard material. The tube body has projected parts and depressed parts. A cover is provided over an outer surface of the tube body. The cover is made of elastic material. The cover is in contact with around the projected parts of the tube body and formed over the depressed parts of the tube body so that a vacant space is formed between the tube body and the cover.